1. Technical Field
The disclosure relates to a communication system and more particularly to a multiple input and multiple output wireless communication system with an expansion module.
2. Related Art
Under the flourishing development of broadband wireless communication technology, multiple input and multiple output (MIMO) technology is used for WiFi, Wimax as well as LTE to enhance communication capacity. In a common N×N MIMO communication system, each antenna interface has a complete receiving and transmitting system allocated, and each of the complete receiving and transmitting system at least includes a radio frequency (RF) front end module, a modulator and a demodulator, a baseband processing module and a media access controller (MAC).
Common commercial system-on-a-chip has developed to a stage that, the modulators, the demodulators, the baseband processing modules and the media access controllers (MACs), and even the radio frequency (RF) front end modules required for 3×3 MIMO system are integrated into a single chip, providing users a solution with powerful functions at low costs. As the number N of MIMO interfaces increases, the entire N×N MIMO system becomes more complicated. Therefore, 3×3 MIMO system is the most advanced level infrastructure seen presently measured by commercial application and mass production as standards. However, the number of the antenna interfaces of the 3×3 MIMO system is no longer qualified to meet the requirements of special applications. High level N×N MIMO system not only can enhance system communication capacity, but can also offer capabilities common communication system can not provide if the features of multiple inputs and multiple outputs are properly used. But the problems of system complexity and increased costs arise, so products being embodied practically are mostly limited to low antenna interface number.